1. Field of the Invention
The present invention concerns a method of manufacturing laminated ceramic material having internal electrodes.
2. Description of the Prior Art
Conventional laminated ceramic material has been manufactured, as typically shown by laminated capacitors or laminated piezoelectric actuators, by a method of printing a metal paste such as sivler or a silver-palladium alloy on a green ceramic sheet, applying press bonding to a plurality of such sheets in stack and, thereafter, decreasing and sintering them.
However, since the sintering temperature of ceramics is high (1300.degree.-1800.degree. C.), the conventional method involves a problem that silver is melted upon sintering because of low melting point of silver.
In view of the above, for preventing melting of silver, a silver-palladium alloy having a higher melting point than silver is prepared by using palladium, so that melting does not occur even at a sintering temperature of ceramics.
However, under the above-mentioned high temperature condition, since the silver-palladium alloy easily diffuses into the ceramics, there is a problem that the voltage withstand or insulation resistance of the ceramic material is reduced.
Further, although a paste of noble metal such as platinum is also used in view of its smaller reactivity with ceramics and high melting point, this results in a significant problem in that the cost is as high as silver.